As shown in FIG. 1, a backlight of a conventional liquid crystal module includes an LED light strip 10, a light guide plate 20 and so forth. Specifically, the light guide plate 20 includes a light-entering surface 21, a light-exiting surface 22 adjacent to the light-entering surface 21 and a bottom surface 23 opposite to the light-exiting surface 22, and the LED light strip is arranged on a side of the light-entering surface 21 of the light guide plate 20. Light emitted from the LED is incident to the light guide plate 20 to achieve a total internal reflection, and is propagated in the light guide plate 20. When the light is incident to the grid-points on the bottom surface 23 of the light guide plate 20, a diffuse reflection occurs, which changes the original light propagation angle and deteriorates the total internal reflection. And then light emits from the light-exiting surface 22 of the light guide plate 20 and forms a surface light source.
As shown in FIG. 1 and FIG. 2, in the backlight of the conventional liquid crystal module, the LED light strip includes a printed circuit board (PCB) 11 and a plurality of LEDs 12 which are arranged and spaced on the PCB 11. A gap 30 is formed between two adjacent LEDs 12, which have rectangular package structures. As shown in FIG. 3, since there is no light possible to emit into the light guide plate 20, little light emits at a position which is located on a side, near to the LED light strip, of the light guide plate 20, and at which the gap 30 between the two adjacent LEDs 12 is located, thereby forming a region darker than surrounding regions. Thus, a hotspot phenomenon having alternate light regions and dark regions occurs on the display screen of the liquid crystal module.